Trying to persuade other by an appeal to their feelings and respect for a certain tradition. In other words:

X is traditional

Therefore X is good (or acceptable)

The reason this line of argument is fallacious is a hidden premise: “Whatever is traditional is acceptable”. Immediately we realize such is not the case. Slavery and sexism were (and still are) traditions in different societies. We now do not consider them acceptable, and if we find them in a society today (such as Islamic societies) we condemn them. “Tradition” is not “reason”.

Example: During the course of her carrier, the prime minister of Australia, Julia Gillard, was questioned about the issue of gay marriage numerous times. Her replies were usually a matter of dancing around the question, starting with “Our position…” or “I and the Labour party have a clear position…”. She usually avoided answering “Why?”, instead repeated her disagreement in different ways.

However, there were some cases which she did try to answer, and that is when our first fallacy is clearly shown. As the Daily Telegraph report here reads, Ms. Gillard tried to justify her disagreement with gay marriage as follows:

“I think that there are some important things from our past that need to continue to be part of our present and part of our future,” she said. “If I was in a different walk of life, if I’d continued in the law and was partner of a law firm now, I would express the same view, that I think for our culture, for our heritage, the Marriage Act and marriage being between a man and a woman has a special status.”

Surely, if we wish to agree with Ms. Gillard, as we saw above we may as well continue slavery and misogyny. After all, they were important parts of our culture and heritage. There is one more thing that is indeed not traditional: Women as prime ministers. I suspect Ms. Gillard should resign according to her own logic.

This fallacy is also important to note in defense of things that may actually be good. Take the whole different celebrations (such as Christmas) that most cultures have around the world. If one asks what is the point of celebrating Christmas (or any other celebration), one may wish to defend the so called “tradition” of Christmas simply because it is a part of the American culture or heritage. But such defence falls into the same category of fallacious argument: If Christmas (or any celebration) is “good”, that does not come from it being a tradition. Traditions are not reasons.

In such case we may wish to argue about the good effects that such celebrations can have on the society. Or perhaps based on the fact that having such celebrations can have positive impact on individual lives.